Method of cladding steel



Main-.h 18,1941.

T. B. ,cl-:ACE Y METHOD OF CLADDING STEEL Filed Nov. 5, 193s jm/enor.'7/2077262615: @flaca Patented Mar. 18, 1941 UNITED STATES ,PATENTori-ICE METHOD or cLAnmNG STEEL Thomas B. Chaco, Winnetka, Ill.Application November 5, 193s, serial No. 239,086

3 Claims.

My invention relates generally to cladding met.- al, and it particularlyrelates to cladding steel 'with a facing of copper or copper base alloy.

In order to produce sheets, plates, or strips of composite metaleconomically, ithas been found that it is necessary to rst provide arelatively thick slab of composite metal. thick composite metal slab canbe reduced to sheets, plates, or strips of the desired thickness byordinary steel mill rolling practice. Thus, a slab of steel six inchesor more in thickness may be cladded with a layer of copper or copperalloy one or two inches in thickness and the composite slab so formed,can be reduced to composite metal y sheet of approximately any desiredthickness, such, for example, as one-half or one-quarter of an inch. Theadvantage of such a. method lies in the fact that b-y starting with arelatively thick slab and reducing it to relatively thin sheets orplates, the initial welding or bonding surface is greatly reduced.

However, the cladding of a relatively thick slab of steel witha layer ofcopper or copper alloy is not without its diiculties. The conditions tobe met are, that, the surface of the steel slab must be cleaned andfreed from scale or other impurities; the slab must be preheated toaround the melting point of the cladding metal; the cleaned surface mustbe protected from oxidation during the cladding operation; and, themolten cladding metal must be maintained and conned to contact with thecleaned surface long enough for it to become integrally bonded thereto.'Iwo of the most diicult of these conditions to be met are; theprotection of the cleaned surface of the preheated slab from oxidationand the confinement of the molten cladding metal to the surface longenough for the desired bonding to be effected.

The object of my invention, generally stated, is to provide for claddinga relatively thick slab of backing metal with a layer of facing metal,in which conventional technique and equipment are used. Y

Another object of-my invention is to protect the bonding surface of theslab of backing metal from oxidation during preheating.-

Another important object of my invention is to confine the moltencladding metal to the surface to be cladded during the bonding operationin an improved manner. l

Another object of my invention is to provide for freeing slag and likeinclusions from the cladded surface.

Other objects from my invention will, in part, be obvious and in partappear hereinafter.

For a more complete understanding of the nature and scope of myinvention, reference may be had to the following detailed descriptiontaken in connection with the accompanying drawing, in which:

'I'his relatively metal.

Figure 1 shows an assembly with a slab of backing metal by which it maybe preheated with its cleaned surfaceV protected from oxidation;

Figure 2 illustrates how the preheated slab may be transferred to a moldfor cladding with a coating of slag adhering to its cleaned surface;

' Figure 3 shows the preheated slab of backing metal placed and securedin one type of mold construction that may be used;

Figure 4 is a sectional view taken on line 4-4 of Figure 3 illustratinghow the mold space may be poured with cladding or facing metal; and

Figure 5 illustrates how the mold may be tilted after pouring in orderto float any slag or similar inclusions from the cladding surface to thetop of the molten cladding metal.

Referring now particularly to Figure 1 of the drawing, a steel backingslab I0 is shown, a surface I I of which it is desired to clad with afacing 'I'he steel backing slab I0 ,is of substantial thickness, forexample six inches or more, and the surface II is cleaned by picklingand/or sand blasting. In order to prevent oxidation of the surface II`during the preheating of the slab I0 it is disposed in a pan I2containing powdered slag or ux I4. 'I'he pan I2 is relatively shallow ascompared with the thickness of the slab I0 and may be made of steel,cast iron or a suitable re. fractory material. Spacers I3, of refractorymaterial are provided to space the slab I0 from the bottom of the panI2. 'I'he powdered slag or ux Il may be powdered glass, borax, boricacid or other suitable material. Sufficient of the powdered slag I 4should be used so that when it is melted it will extend up around thesides of the slab III a little distance', thereby insuring that thesurface Il will not be exposed. The weight of the slab Il compresses thepowdered slag or flux I4 and forces it to compress aroundvits edges andsides,thereby protecting the cleaned surface I-I before preheating. Ifdesired, the slag I4 may be rst melted and heated so that it is liquid,and then may be poured into the pan I2 after the slab III has beenpositioned therein. However, by using the slag or flux Il in powderedform the surface II may be very well protected and there appears to beno advantage in first melting the slag or ilux I4 and pouring it intothe pan I2.

After the assembly shown in Figure 1 has been prepared, the slab I0 isthen ready to be preheated. The preheating furnace used for this may beof the pusher type, so that the slabs I0 together with the pan `I2 arepushed through from the inlet side and out theoutlet side during thepreheating period, or it may be of a car-v bottom type comprisingindividual cars holding one or more slab and pan assemblies. The slab Ilmay be preheated to a temperature of around 2250 F., at whichtemperature the powdered flux on or lslag I4 is molten and protects thesurface Il from the furnace atmosphere.

The slab I0 having been preheated to the desired degree, is removed fromthe preheating furnace and transferred to a. conventional open mold 20shown in Figure 3 of the drawing. The mold 20 should be slightly largerthan the slab IIJ and the sides may well slope outwardly to some extent.The transfer of the preheated slab I0 from the preheating furnace to thempld 20 is illustrated in Eigure 2 of the drawing. In this figure a pairof tongs I5 are shown carrying the slab IIl'with the surface II on thebottom. `A

Referring now particularly to Figure 3 of the l drawing, the preheatedslab I0 is shown in its position in the mold 20. The slab I0 is spacedfrom the bottom 2| of the mold 20 a distance equal tothe thickness of.the desired layer of facing metal by loose spacer blocks 22. The spacerblocks 22 can be of steel which are later cast in the facing metal asinserts and may be later rolled down with the composite slab and thentrimmed olf. In order to secure the slab IIJ in place in the mold 20, ayoke 23 is provided carrying heavy screws 24. After the slab I0 has beenset in the mold 20 on the spacer blocks 22 the yoke 23 may be put inplace and the screws 24 tightened down until they engage the slab I0 andfirmly hold it in place. It will be understood that the yoke 23 may bereplaced by any other suitable securing means desired.

With a View to showing how a layer of facing metal may be cladded on thesurface II, reference may now be had particularly to Figure 4 of thedrawing. The inside of the mold 20 is first prepared with a molddressing 25 to prevent the molten facing metal from adhering thereto.Molten facing or cladding metal 26 may be poured into one side of themold 20 from the ladle 21. Suiiicient facing metal 26 is-poured so thatthe space between the surface II of the slab I0 and the bottom 2I of thempld 20 will be filled, and the molten facing metal 26 will extend alittle way up the sides of the slab I 0.

Since the slag I4 and other like impurities are lighter than the moltenfacingmetal 26, they will float to the top thereof. However, in order tomake sure that no impurities remain in contact with the surface II toprevent the bonding of the facing metal 26 thereto, the entire moldassembly, shown in Figure 4, may be tilted at an angle as shown inFigure 5 of the drawing. 'I'his insures that any slag I4 or otherinclusions remaining in contact with the surface II will be worked outand oated un to the top of the molten facing metal 26. After all of theslag I4 or other impurities have thus been worked out, the wholeassembly is returned to a. horizontal position.

The preheated slab I0 will maintain the molten facing metal 26 in themolten condition for some time, depending largely on the temperature towhich it has been preheated. c In this manner the length of timerequired for the bonding of the facing metal 26 to the surface II may besecured.

After the facing metal 26 has Abonded to the surface II and solidified,the slab I0 may be removed from the mold 20 and rolled down to a sheetor plate of the desired thickness. The excess facing metal 26, slag I4and other inclusions along the edges are of course trimmed oif afterrolling.

By using the method outlined above it is possible to clad a surface of arelatively thick steel backing slab with a layer of facing metal usingconventional foundry methods, technique, and equipment. The requirementsof protecting the cleaned cladding surface from oxidation and conningthe molten cladding metal to the clean surface during bonding have thusbeen satisfactorily and economically met.

Since certain changes may be made in the foregoing method without'departing from the spirit and scope thereof, it is intended that allmatters shown in the accompanying drawing as set forth in the foregoingdescription shall be interpreted as illustrative and not in a limitingsense.

I claim as my invention: y

1. The method of cladding a single surface which is to be worked androlled of a slab of backing metal with a layer of facing metal whichcomprises; preheating said slab with said surface submerged in moltenslag, transferring the preheated slab into a mold in such manner thatsaid surface is on the bottom and spaced from the floor of said mold adistance equal to the desired thickness of said facing layer, securingsaid slab in its position in said mold, pouring facing metalv into saidmold, tilting said mold to allow substantially all slag to rise to thesurface of the molten facing metal.

2. The method of cladding a single surface which is to be worked androlled of a slab of backingmetal'with a layer of facing metal'whichcomprises; preheating said slab with its lower face submerged in amolten slag, transferring the preheated slab with a protecting coat ofslag adhering thereto into a mold, said lower. face being spaced fromthe bottom of said mold a distance equal to the thickness of the facinglayer desired, pouring molten facing mletal into said mold to more thanfill said space between said lower face and the bottom of said mold,tilting said mold so lled to allow substantially all the slag to rise tothe top of the molten facing metal, and returning said mold to itshorizontal position to allow the facing metal to bond to said loweiface.

3. The method of` cladding a single surface which is to be worked androlled of a. slab of backing metal with a layer of facing metal whichcomprises; preheating said slab with said surface submerged in moltenslag, transferring the preheated slab into a mold in such manner thatsaid surface is on the bottom and spaced from the floor of said mpld adistance equal to the desired thickness of said facing layer, securinglsaid slab in its position in said mold, pouring facing metal into saidmold, tilting said mold to allow substantially all the slag to rise tothe surface of the'molten facing metal, and returning said mold to itsoriginal position, said lower face to be cladded being unexposed to theatmosphere during its transfer and during the pouring of said facingmetal.

' 'rHoMAs B. CHACE.

